Task 1
Directions: After reading the following passage, you will find 5 questions or unfinished statements, numbered 36 through 40. For each question or statement there are 4 choices marked A, B, C, and D. You should make the correct choice.
Accidents are caused; they don' t just happen. The reason may be easy to see: an overloatled tray, a shelf out of reach, or a patch of ice on the road. But more often than not there is a chain of events leading up to the misfortune---frustration (挫折),
According to the author, the accidents are mainly caused by ______.

A. external (外部的) conditions
B. people's internal (内部的) conditions influenced by physical or mental factors
C. slippery (滑的) rod&
D. a chain of events